Answer:
(I don't know where to round the numbers to, so I'll just put the full areas)
The answer to 9. is: 380.132711 mm², and the answer to 10. is: 19.6349541 ft².
Step-by-step explanation:
The formula for the area of a circle is A = πr². (A = area, π = pi, r = radius.) When you substitute the variables in the formula for the values of question #9, you get A = π(11)². (It's 11 because the radius is half of the diameter, which in this case is 22 mm.) And when you substitute the variables for the values of question #10, you get A = π(2.5)². And from there, you just finish the equations. Hope this helps :)
